Depends on your definition of 'Multi-tasking'.

In as far as PICs can only excute one instruction at a time, then the answer is No.

But if you factor in all the additional hardware such as ADC's comparators, Timers, USART etc etc that can operate autonomously from your main program, then the answer is most certainly Yes.

By using PBP's PULSIN instead of say Caputure & Compare and SERIN (or SERIN2) instead of the onboard USART directly, you are relinquishing control of your PIC for long periods of time (as you have already concluded). Your skill as a programmer will decide how much you can have on the go seamlessly, and accomplish everything on one PIC or go for the simpler, but more expensive route and have two.